A randomized trial in a massive online open course shows people don't know what a statistically significant relationship looks like, but they can learn

Scatterplots are the most common way for statisticians, scientists, and the public to visually detect relationships between measured variables. At the same time, and despite widely publicized controversy, P-values remain the most commonly used measure to statistically justify relationships identified between variables. Here we measure the ability to detect statistically significant relationships from scatterplots in a randomized trial of 2,039 students in a statistics massive open online course (MOOC). Each subject was shown a random set of scatterplots and asked to visually determine if the underlying relationships were statistically significant at the P < 0.05 level. Subjects correctly classified only 47.4% (95% CI: 45.1%-49.7%) of statistically significant relationships, and 74.6% (95% CI: 72.5%-76.6%) of non-significant relationships. Adding visual aids such as a best fit line or scatterplot smooth increased the probability a relationship was called significant, regardless of whether the relationship was actually significant. Classification of statistically significant relationships improved on repeat attempts of the survey, although classification of non-significant relationships did not. Our results suggest: (1) that evidence-based data analysis can be used to identify weaknesses in theoretical procedures in the hands of average users, (2) data analysts can be trained to improve detection of statistically significant results with practice, but (3) data analysts have incorrect intuition about what statistically significant relationships look like, particularly for small effects. We have built a web tool for people to compare scatterplots with their corresponding p-values which is available here: http://glimmer.rstudio.com/afisher/EDA/.Comment: 7 pages, including 2 figures and 1 tabl

Evaluating the Attractiveness of Pacific Northwest Native Plants to Insects and Gardeners

Due to a growing body of literature documenting declines in pollinator populations, there has been increased public interest in pollinator conservation. In urban and suburban landscapes, many gardeners and urban land managers are interested in gardening for pollinators, particularly bees. Simultaneously, many homeowners and municipalities are interested in other aspects of ecological gardening, including drought tolerant plantings, and even gardening for general biodiversity to support arthropods amidst global insect declines. Native plants are of particular interest in habitat plantings, as their purported benefits include providing better quality habitat for native arthropods and needing fewer inputs due to water adaptation. However, in most regions of the United States, including the Pacific Northwest, there have been no empirical studies on the most attractive plants to bees. Better understanding the abundance and richness of bee communities attracted to native plants will help regional urban pollinator conservation programs. However, to truly be successful in urban pollinator plantings, native plants should also have aesthetic qualities that fit into ornamental gardens and landscapes. I conducted a three-year field study (2017-2019) to investigate the relative attractiveness of 23 native Pacific Northwest plant species to bees, and included four non-native garden plants commonly used in gardens as comparators. Additionally, I sought to characterize the abundance and richness of herbivores, predators, parasitoids, and detritivores supported by these plant species. I installed these plants in 1 m2 plots at Oregon State University’s North Willamette Research and Extension Center, with five replicates of each species and six meters between plots. During the week of peak bloom and the weeks preceding and following, I performed five-minute bee counts to assess bee abundance. To assess bee species richness, I used an insect vacuum to sample each plot, with four overhead passes to collect bee specimens for identification in the lab. In doing this, I also collected other insects present on the plant. In the lab, we identified bees to species and other insects to the lowest practical taxonomic resolution. To assess gardener preferences of our study plants, I designed an online survey disseminated via email listservs and social media. The first survey asked gardeners to rate how likely they would be to garden with 23 flowering plants native to the Pacific Northwest United States on a five-point Likert scale. I created a second survey that again asked gardeners to rank the likelihood they would garden with a subset of 11 of these 23 native plants on a five-point Likert scale, before and after receiving a one or two facts about the bee species each flower attracted. Most native plants were ranked relatively high by gardeners. Short messages about the bees associated with specific plants raised gardeners’ impressions of native plants. In Chapter 2, I analyze the bee communities associated with my study plants. Over the three years, Douglas’ aster (Symphyotrichum subspicatum), California poppy (Eschscholzia californica), varileaf phacelia (Phacelia heterophylla), Canada goldenrod (Solidago canadensis), farewell-to-spring (Clarkia amoena), globe gilia (Gilia capitata), and Oregon sunshine (Eriophyllum lanatum) all attracted high bee abundance and species richness. Additionally, several native plants were consistently more attractive to bees than the exotic comparator species. The bee communities associated with the study plants were significantly different. Thus, using a combination of these plants in landscape designs and plantings might maximize the ability of a garden to support a diverse community of bees. I analyze the communities of herbivores, natural enemies, and detritivores in Chapter 3. Significant differences were found between the insect communities supported by the various study plants. In particular, Douglas’ aster, goldenrod, pearly everlasting (Anaphalis margaritacea), yarrow, and farewell-to-spring attracted a high abundance and species richness of parasitoids and predators. These plants also supported a high overall herbivore abundance, indicating they may be good candidates to provide resources at the first trophic level for broader conservation plantings, or as insectary plants to promote biological control. In Chapter 4 I share the results of two gardener surveys assessing gardeners’ impressions of study plants. The first survey revealed a high level of acceptance of native plants by home gardeners. However, there was relatively little overlap between the plants most attractive to gardeners and those most attractive to bees (identified in Chapter 2). The second survey found that gardeners’ stated likelihood of planting significantly increased after seeing photos of and reading a small amount of information about the bees supported by each plant. Replies to open ended question boxes revealed gardeners were most concerned with the weediness of and aesthetics of candidate plants, and that they felt positively about the ecological benefits and the aesthetics of many species. Many gardeners wanted more information about the study plants, before committing to planting them in their garden. Finally, in Chapter 5, I created an Extension document to bridge that gap we identified, and provide the public with easily digestible information about the top bee plants via fact sheets and compelling visuals

Inhibition of microbial sulfate reduction in a flow-through column system by (per)chlorate treatment.

Microbial sulfate reduction is a primary cause of oil reservoir souring. Here we show that amendment with chlorate or perchlorate [collectively (per)chlorate] potentially resolves this issue. Triplicate packed columns inoculated with marine sediment were flushed with coastal water amended with yeast extract and one of nitrate, chlorate, or perchlorate. Results showed that although sulfide production was dramatically reduced by all treatments, effluent sulfide was observed in the nitrate (10 mM) treatment after an initial inhibition period. In contrast, no effluent sulfide was observed with (per)chlorate (10 mM). Microbial community analyses indicated temporal community shifts and phylogenetic clustering by treatment. Nitrate addition stimulated Xanthomonadaceae and Rhizobiaceae growth, supporting their role in nitrate metabolism. (Per)chlorate showed distinct effects on microbial community structure compared with nitrate and resulted in a general suppression of the community relative to the untreated control combined with a significant decrease in sulfate reducing species abundance indicating specific toxicity. Furthermore, chlorate stimulated Pseudomonadaceae and Pseudoalteromonadaceae, members of which are known chlorate respirers, suggesting that chlorate may also control sulfidogenesis by biocompetitive exclusion of sulfate-reduction. Perchlorate addition stimulated Desulfobulbaceae and Desulfomonadaceae, which contain sulfide oxidizing and elemental sulfur-reducing species respectively, suggesting that effluent sulfide concentrations may be controlled through sulfur redox cycling in addition to toxicity and biocompetitive exclusion. Sulfur isotope analyses further support sulfur cycling in the columns, even when sulfide is not detected. This study indicates that (per)chlorate show great promise as inhibitors of sulfidogenesis in natural communities and provides insight into which organisms and respiratory processes are involved

Compression Molding and Novel Sintering Treatments for Alnico Type-8 Permanent Magnets in Near-Final Shape with Preferred Orientation

Economic uncertainty in the rare earth (RE) permanent magnet marketplace, as well as in an expanding electric drive vehicle market that favors permanent magnet alternating current synchronous drive motors, motivated renewed research in RE-free permanent magnets like “alnico,” an Al-Ni-Co-Fe alloy. Thus, high-pressure, gas-atomized isotropic type-8H pre-alloyed alnico powder was compression molded with a clean burn-out binder to near-final shape and sintered to density \u3e99% of cast alnico 8 (full density of 7.3 g/cm3). To produce aligned sintered alnico magnets for improved energy product and magnetic remanence, uniaxial stress was attempted to promote controlled grain growth, avoiding directional solidification that provides alignment in alnico 9. Successful development of solid-state powder processing may enable anisotropically aligned alnico magnets with enhanced energy density to be mass-produced

Does risk of progression from Barrett’s esophagus to esophageal adenocarcinoma change based on the number of non-dysplastic endoscopies?

Funding: This study was funded in full by the National Institutes of Health, grant number (NIH P30DK056338‐16). The Northern Ireland Barrett’s register was funded by the UK Medical Research Council, Cancer Focus Northern Ireland (formerly the Ulster Cancer Foundation), NI HSC R&D Office, and Cancer Research UK. The Northern Ireland Cancer Registry is funded by the Public Health Agency.Peer reviewedPostprin

The White Dwarf Cooling Sequence of NGC6397

We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 magnitudes in depth, with an apparent cutoff at magnitude F814W=27.6. We demonstrate, using both artificial star tests and the detectability of background galaxies at fainter magnitudes, that the cutoff is real and represents the truncation of the white dwarf luminosity function in this cluster. We perform a detailed comparison between cooling models and the observed distribution of white dwarfs in colour and magnitude, taking into account uncertainties in distance, extinction, white dwarf mass, progenitor lifetimes, binarity and cooling model uncertainties. After marginalising over these variables, we obtain values for the cluster distance modulus and age of \mu_0 = 12.02 \pm 0.06 and T_c = 11.47 \pm 0.47Gyr (95% confidence limits). Our inferred distance and white dwarf initial-final mass relations are in good agreement with other independent determinations, and the cluster age is consistent with, but more precise than, prior determinations made using the main sequence turnoff method. In particular, within the context of the currently accepted \Lambda CDM cosmological model, this age places the formation of NGC6397 at a redshift z=3, at a time when the cosmological star formation rate was approaching its peak.Comment: 56 pages, 30 figure